Conventional vehicles for present street and road traffic are powered by internal combustion engines. Electrically powered vehicles also are known, some of which are supplied by batteries and others by solar power equipment. Battery-powered drives have long been used for railway station carts, fork lifts and the like.
The essential drawbacks of electrically powered vehicles are that battery recharging demands substantial time or necessitates expensive exchange of the batteries, battery capacity being significantly limited because of weight and also because the required controls entail additional losses. Also, the batteries, drive motors and controls are heavy, degrading the energy picture.
An electrical wheel-drive for motor vehicles, in particular for hybrid automobiles, is known from the nearest document of the state of the art, namely EP 46 997 A2, which describes a system in which one electronically rpm-controlled, polyphase, brushless electric motor is associated with each wheel. The wheel-hub motors are multi-gap axial field motors of which the rotors replace the wheel drums and brake disks and of which the stators replace the brake pads and splash-guard plates. The stator comprises inwardly projecting support elements carrying pancake annular coils mounted in the air gaps between the pole pieces.
The annular coils consist of scaled, laminated windings with use of ribbon conductors.
The rotor for this wheel drive is mechanically very complex and its weight is high. Accordingly, when the vehicle is decelerated or accelerated, substantial inertia is encountered. Moreover, the drive control circuit is very simple and accordingly it does not make optimal use of available energy.
A disk-rotor motor is known from the periodical etz-A, vol. 94 (1973, 10, pp 547), which may be used as vehicle drive. This disk-rotor motor however is not such in the rigorous sense, because its winding planes are radial to the motor axis, whereas conventional disk-rotor motors make use of plastic boards with copper-laminated conducting strips on one or both sides.
A three phase AC double-power locomotive is known from BBC News, 4, pp 135-140, which comprises a DC-DC converter compensating large voltage differences in the power line. The document discloses an adjustable pulse-width control of which the output voltage is applied to the three-phase AC coil of the motor.
Lastly, German Auslegeschrift 20 10 594 discloses a motor vehicle with three-phase AC drive, a three-phase AC motor being present at two mutually opposite edges of the vehicle and of which the control is affected by the steering of the driver. No provision is made for a three-phase AC disk-rotor motor.